Rich variety of defects in ZnO via an attractive interaction between O vacancies and Zn interstitials: origin of n-type doping.

As the concentration of intrinsic defects becomes sufficiently high in O-deficient ZnO, interactions between defects lead to a significant reduction in their formation energies. We show that the formation of both O vacancies and Zn interstitials becomes significantly enhanced by a strong attractive interaction between them, making these defects an important source of n-type conductivity in ZnO.